1. Field of the Invention
The present invention relates generally to systems and software for determining aberrations, and more specifically to systems and software for determining aberrations of an input wavefront by correcting for, compensating for, or reducing system errors.
2. Description of the Related Art
Wavefront imaging system may be generally considered to be systems for transferring optical information contained in an object or input wavefront from an object space to an image space containing an image or output wavefront generally located at an image plane. A wavefront sensor, containing a detector or detector array such as a CCD or CMOS detector array, is generally placed at or near an image plane within the image space in order to provide one or more electronic or digital images of the image wavefront. The wavefront sensor may include additional optics disposed at or near the image space to further transfer or process the image wavefront. For example, a lenslet array may be disposed at or near the image plane in order to sample various portions the image wavefront. In some cases, a recording media such as a holographic plate and a reference beam may be provided to record the wavefront for later reconstruction. In any case, the recorded information in the image plane or space is generally used to provide information contained in the original object wavefront.
The transfer of optical information by the wavefront imaging system to the wavefront sensor is, however, generally imperfect. At a minimum, the effects of diffraction, which arise from the use of a finite system aperture, will limit the ability of the wavefront imaging system to transfer information contained in the object space to the conjugate image space. In addition, the wavefront imaging system will produce other errors or aberrations during the transfer process, for example, aberrations produced by imperfect optical elements within the system and/or misalignment between these optical elements.
In prior art wavefront imaging systems, aberrations or errors of the imaging system are typically not accounted for, which can lead to errors in accurately determining aberrations of an input wavefront, which has passed through an aberrated imaging system, based on measurements of an output wavefront. Rather, the imaging system is designed so as to minimize system optical aberrations, and is carefully aligned to reduce alignment errors. However, the inventor have found that even relatively small system aberrations or misalignment can lead to large errors in calculating the magnitude of higher order aberration terms of the original input wavefront.
In some cases, the errors or aberrations produced by the optical imaging system may depend, not only on the system aberrations themselves, but also on the aberrations contained in the original input wavefront.
Accordingly, better methods and systems are needed to provide more accurate calculation of the aberrations contained in an input wavefront after it has passed through a wavefront imaging system containing system aberrations and misalignments.